Acid-base chemistry acids Lewis bases

For most aqueous acid-base chemistry, the Lewis definitions are too general and lack the symmetry of the acid-conjugate base relationship. We will mostly use the Bronsted-Lowry definitions. 

In a Lewis acid-base reaction, a Lewis base donates an electron pair to a Lewis acid. Most of the reactions in organic chemistry involving movement of electron pairs can be classified as Lewis acid-base reactions. Lewis acid-base reactions illustrate a general pattern of reactivity in organic chemistry. 

Many important biochemical reactions involve Lewis acid Lewis base chemistry Carbon dioxide is rapidly converted to hydrogen carbonate ion m the presence of the enzyme carbonic anhydrase... 

The reaction between a Lewis acid R3M and a Lewis base ER3, usually resulting in the formation of a Lewis acid-base adduct R3M—ER3, is of fundamental interest in main group chemistry. Numerous experiments, in particular reactions of alane and gallane MH3 with amines and phosphines ER3, have been performed [14]. Several general coordination modes, as summarized in Fig. 2, have been identified by X-ray diffraction. 

C21-0040. Describe in detail the bonding in AI2 Clg. Explain the formation of the molecule in terms of Lewis acid-base chemistry. 

Up to this point, we have dealt with the subject of acid-base chemistry in terms of proton transfer. If we seek to learn what it is that makes NH3 a base that can accept a proton, we find that it is because there is an unshared pair of electrons on the nitrogen atom where the proton can attach. Conversely, it is the fact that the hydrogen ion seeks a center of negative charge that makes it leave an acid such as HC1 and attach to the ammonia molecule. In other words, it is the presence of an unshared pair of electrons on the base that results in proton transfer. Sometimes known as the electronic theory of acids and bases, this shows that the essential characteristics of acids and bases do not always depend on the transfer of a proton. This approach to acid-base chemistry was first developed by G. N. Lewis in the 1920s. 

Lewis acid-base chemistry provides one of the most useful tools ever devised for systematizing an enormous number of chemical reactions. Because the behavior of a substance as an acid or a base has nothing to do with proton transfer, many other types of reactions can be considered as acid-base reactions. For example,... 

The rational design of chelating agents as antidotes requires a careful consideration of acid-base chemistry. Metal ions are Lewis acids, while the chelating agents or ligands are Lewis bases. The concepts of hardness and softness may be used to describe systematically the interaction between them. A hard metal cation is one that retains its... 

Another particular area of organic catalysis is that of Lewis acid activation by a Lewis base. This catalysis represents a powerful means of modulating the electron density of weakly electron-withdrawing centers. Such an interaction operates under well-defined circumstances between donor and acceptor entity, and results in a decreased electron density on the central atom in question. This chemistry is described in greater detail in Chapter 10. 

A very useful book discussing many aspects of acid-base chemistry in terms of the Lewis definition is Jensen, W. B. The Lewis Acid-Base Cnncept.s An Overview. Wiley New York, 1980. 

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